Preparation and thermal characterization of films containing liquid crystals in a cellulose acetate substrate for externally regulated applications

Abstract

Two different series of polymer dispersed liquid crystal (PDLC) films were prepared for their future use as externally controlled electrolytes in direct methanol fuel cells (DMFC). The liquid crystals used in this work were commercial cholesteryl oleyl carbonate (COC) and n-(4-methoxybencylidine)-4-butylanilyne (MBBA); cellulose acetate (CA) was used as the polymer substrate. All the films were characterized by differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA) to analyze the existence of interactions between the components, the modification of the liquid crystal behavior and the thermal stability of the films. The two series of films exhibited very different behaviors. While the films containing CA and COC maintained most of the properties characteristic of the pure components, including the COC mesomorphism, the analysis of films containing CA and MBBA revealed the existence of strong interactions between the components that promoted the inhibition of the MBBA mesomorphic behavior.

Cellulose acetate-poly{[9,9-bis(6′-N,N,N-trimethylammonium)hexyl]fluorene-phenylene} bromide blends: Preparation, characterization and transport properties

“…In the first heating scan, a broad endothermic band can be observed between 25 °C and 100 °C. Since this process does not appear in the second heating, it can be attributed to water desorption from CA [24,35], in complete agreement with the TG data. In the cooling step, a glass transition (T g ) can be observed, that also appears in the second heating scan just before melting transitions for all samples.…”

“…A main thermal event can be seen in all cases, centred at 362 °C, that corresponds to the pyrolysis of the polymer backbone structure. In addition, there is an initial mass loss region at around 100 °C, that is likely to be associated with the loss of water in CA (also observed in DSC experiments on second heating of samples) [35].…”

“…Table 1 shows the main thermal data obtained from the TG-DTG curves, including the temperature at which 5% of the total mass is volatilized (T 5 ) and temperature at the maximum degradation rate (T max ). T 5 provides an accurate idea of the thermal stability since the identification of the initial decomposition temperature (mass loss near to 0%) is extremely difficult because of slight variations in mass loss in this zone correspond to large temperature variations [35,36].…”

Transparent nanostructured cellulose acetate films based on the self assembly of PEO-b-PPO-b-PEO block copolymer

“…In particular, cellulose acetate (CA) has been extensively used as matrix to design this kind of novel nanocomposites taking into account its cost effectiveness, relatively easier manufacturing, non-toxicity, good biocompatibility and mechanical rigidity (Braganca & Rosa, 2003;Fidale et al, 2010;Fischer et al, 2008). Accordingly, numerous papers related to the improvement of CA properties by combining it with different polymers such as poly(ethylene oxide) (Kamal, Abd-Elrahim, & Lotfy, 2014), poly(-caprolactone) (Ali, 2014), poly(isophthalamide) (Jayalakshmi et al, 2014), polysiloxane (Brandao, Yoshida, Felisberti, & Gonç alves, 2013) and additives such as liquid crystals (Martínez-Felipe, Ballester-Sarrias, Imrie, & Ribes-Greus, 2010;Shuiping, Lianjiang, Weili, Xiaoqiang, & Yanmo, 2010), clay (Park, Misra, Drzal, & Mohanty, 2004) and graphene (de Moraes et al, 2015;Gopiraman, Fujimori, Zeeshan, Kim, & Kim, 2013;Jeon, An, & Jeong, 2012) have been published. Some researchers have also used starch nanocrystals acetate (Huang, Wu, Yu, & Lu, 2015) and hydroxypropyl cellulose (Onofrei et al, 2014).…”

Study of Structure Formation in Side-Chain Liquid Crystal Copolymers by Variable Temperature Fourier Transform Infrared Spectroscopy

“…Multifunctional SCLCPs may be obtained by the introduction of nonmesogenic units into the polymer structure via copolymerisation. Following this approach, several SCLCPs have been designed as potential components in electrolytes for advanced electrochemical technologies, by the incorporation of metal ions, such as alkali metal ions, or ionogens, such as carboxylic and sulfonic acid groups. − Different types of materials containing liquid crystals have been reported recently with a view to controlling their transport properties through the formation of anisotropic morphologies. − …”